Two-stage turbo system and control method for two-stage turbo system

摘要

A two-stage turbo system includes: a high-pressure stage turbocharger having a high-pressure stage turbine disposed in an exhaust passage of an engine; and a low-pressure stage turbocharger which includes a low-pressure stage turbine disposed downstream of the high-pressure stage turbine in the exhaust passage, and which is larger in size than the high-pressure stage turbocharger. The low-pressure stage turbine includes at least two scroll passages including a first scroll passage and a second scroll passage, which together form a scroll part for introducing exhaust gas into a nozzle flow passage of the low-pressure stage turbine. The scroll part is configured such that a first range of the nozzle flow passage into which the exhaust gas passing through the first scroll passage is introduced does not overlap with a second range of the nozzle flow passage into which the exhaust gas passing through the second scroll passage is introduced, in a circumferential direction of the nozzle flow passage.